scholarly journals Concept for an electrostatic focusing device for continuous ambient pressure aerosol concentration

2019 ◽  
Vol 12 (6) ◽  
pp. 3395-3402
Author(s):  
Joseph L. Woo ◽  
Neha Sareen ◽  
Allison N. Schwier ◽  
V. Faye McNeill
Keyword(s):  
Continuous Flow ◽  
Ambient Pressure ◽  
Aerosol Particles ◽  
Particle Diameter ◽  
Aerosol Concentration ◽  
Submicron Particles ◽  
Virtual Impactors ◽  
Unipolar Charger ◽  
Prototype Design

Abstract. We present a concept for enhancing the concentration of charged submicron aerosol particles in a continuous-flow stream using in situ electrostatic focusing. It is proposed that electrostatic focusing can enable the continuous, isothermal concentration of aerosol particles at ambient pressure, without altering their chemical composition. We model this approach theoretically and demonstrate proof of concept via laboratory measurements using a prototype. The prototype design consists of a nozzle-probe flow system analogous to a virtual impactor. The device was tested in the laboratory using submicron, monodisperse stearic acid particles. Particles were charged using a unipolar charger then concentrated using a cylindrical electrostatic immersion lens to direct the charged submicron particles into the sample probe. Under applied lens voltages ranging from 0 V to 30 kV, aerosol concentration increased up to 15 %. Observed particle enrichment varied as a function of voltage and particle diameter. These results suggest that an imposed electric field can be used to increase aerosol concentration in a continuous flow. This approach shows promise in increasing the effective enriched size range of virtual impactors or other continuous-flow methods of collection.

scholarly journals Concept for an electrostatic focusing device for continuous ambient pressure aerosol concentration

2019 ◽  
Author(s):  
Joseph L. Woo ◽  
Neha Sareen ◽  
Allison N. Schwier ◽  
V. Faye McNeill
Keyword(s):  
Continuous Flow ◽  
Ambient Pressure ◽  
Aerosol Particles ◽  
Particle Diameter ◽  
Aerosol Concentration ◽  
Submicron Particles ◽  
Virtual Impactors ◽  
Unipolar Charger ◽  
Prototype Design

Abstract. We present a concept for enhancing the concentration of charged submicron aerosol particles in a continuous flow stream using in situ electrostatic focusing. It is proposed that electrostatic focusing can enable the continuous, isothermal concentration of aerosol particles at ambient pressure, without altering their chemical composition. We model this approach theoretically and demonstrate proof-of-concept via laboratory measurements using a prototype. The prototype design consists of a nozzle-probe flow system analogous to a virtual impactor. The device was tested in the laboratory using submicron, monodisperse stearic acid particles. Particles were charged using a unipolar charger, then concentrated using a cylindrical electrostatic immersion lens to direct the charged submicron particles into the sample probe. Under applied lens voltages ranging from 0 V to 30 kV, aerosol concentration increased up to 15 %. Observed particle enrichment varied as a function of voltage and particle diameter. These results suggest that an imposed electric field can be used to increase aerosol concentration in a continuous flow. This approach shows promise in increasing the effective enriched size range of virtual impactors or other continuous-flow methods of collection.

scholarly journals The ATAL within the 2017 Asian Monsoon Anticyclone: Microphysical aerosol properties derived from aircraft-borne in situ measurements

2021 ◽  
Author(s):  
Christoph Mahnke ◽  
Ralf Weigel ◽  
Francesco Cairo ◽  
Jean-Paul Vernier ◽  
Armin Afchine ◽  
...  
Keyword(s):  
Asian Monsoon ◽  
Asian Summer Monsoon ◽  
Aerosol Particles ◽  
Potential Temperature ◽  
Particle Diameter ◽  
Aerosol Layer ◽  
Mixing Ratio ◽  
Detection Range ◽  
Particle Mixing

Abstract. The Asian summer monsoon is an effective pathway for aerosol particles and precursor substances from the planetary boundary layer over Central, South, and East Asia into the upper troposphere and lower stratosphere. An enhancement of aerosol particles within the Asian monsoon anticyclone (AMA) has been observed by satellites, called the Asian Tropopause Aerosol Layer (ATAL). In this paper we discuss airborne in situ and remote sensing observations of aerosol microphysical properties conducted during the 2017 StratoClim field campaign within the region of the Asian monsoon anticyclone. The aerosol particle measurements aboard the high-altitude research aircraft M55 Geophysica (reached a maximum altitude of about 20.5 km) were conducted by a modified Ultra High Sensitivity Aerosol Spectrometer Airborne (UHSAS-A; particle diameter detection range from 65 nm to 1 µm), the COndensation PArticle counting System (COPAS, for detecting total aerosol densities of submicrometer sized particles), and the Cloud and Aerosol Spectrometer with Detection of POLarization (NIXE-CAS-DPOL). In the COPAS and UHSAS-A vertical particle mixing ratio profiles, the ATAL is evident as a distinct layer between 15 km (≈ 370 K) and 18.5 km altitude (≈ 420 K potential temperature). Within the ATAL, the maximum detected particle mixing ratios (from the median profiles) were 700 mg−1 for diameters between 65 nm to 1 µm (UHSAS-A) and higher than 2500 mg−1 for diameters larger than 10 nm (COPAS). These values are up to two times higher than previously found at similar altitudes in other tropical locations. The difference between the particle mixing ratio profiles measured by the UHSAS-A and the COPAS indicate that the region below the ATAL at potential temperatures from 350 to 370 K is influenced by the fresh nucleation of aerosol particles (diameter

Size-resolved effective density of submicron particles during autumn in the North China Plain

2020 ◽  
Author(s):  
Yaqing Zhou ◽  
Nan Ma ◽  
Zhibin Wang ◽  
Linhong Xie ◽  
Baofang Xie ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Aerosol Particles ◽  
Particle Diameter ◽  
Submicron Particles ◽  
Effective Density ◽  
Rural Site ◽  
Mass Analyzer ◽  
The North ◽  
The North China Plain

<p>Effective density is one of the most important physical property of atmospheric aerosols, which is link to particle formation and aging process. Combined characterization of density, chemical composition and source evolution of aerosol is crucial for understanding their interactions and effects on environment and climate. The effective density of sub-micrometer aerosol particles was investigate at a heavily polluted rural site in the North China Plain from 16 October to 1 November 2019. A tandem technique coupling a Centrifugal Particle Mass Analyzer (CPMA) with a differential mobility analyzer (DMA) and a Condensation Particle Counter (CPC) were used to determine the effective density of ambient aerosol particles with selected diameters of 50, 100, 150, 220 and 300 nm. The measured effective density is higher during clean period than pollution period, with average values ranged from 1.13 to 1.36 g/cm<sup>3</sup>, which is lower than the reported values in Shanghai and Beijing. Similar diurnal cycles of effective density are observed for the five diameters, that is, started to increase in the morning and reached a peak in the afternoon around 13:00-16:00, then decreased and remained at a relative low value during the night. Two valleys are found during morning and evening rush hours for particle diameter smaller than 150 nm, which is likely to stem from the higher fresh emissions such as BC, BBOA and HOA. In most cases, measured particle effective density shows a single-modal distribution. But during clean days, bimodal distribution was observed with an extra low-density mode peaking at around 0.5 -1.0 g/cm<sup>3</sup>, which may be attributed to freshly emitted soot particles.</p>

Numerical simulation of the dynamic formation process of fog-haze and smog in transport tunnels of a hot mine

2016 ◽  
Vol 26 (8) ◽  
pp. 1062-1069 ◽  
Author(s):  
Sheng-hua Zou ◽  
Kong-qing Li ◽  
Qiao-yun Han ◽  
Chuck Wah Yu
Keyword(s):  
Wind Speed ◽  
Numerical Modelling ◽  
Coal Mine ◽  
Aerosol Particles ◽  
Geometric Mean ◽  
Particle Diameter ◽  
Monte Carlo Algorithm ◽  
Hunan Province ◽  
Air Conditioner

Fog-haze and smog can be formed in transport tunnels during artificial cooling by air-conditioner, under hot and high humidity conditions inside a coal mine. The processes of coagulation, condensation, nucleation, crushing and evaporation, which can occur at the same time, can be simulated by a dynamic model. The relationship between the particle size distribution over time and environmental parameters such as wind speed, temperature and relative humidity, during smog formation in transport tunnels in a coal mine was characterised by our numerical modelling and in-situ study of a coal mine in Hunan Province, China. The development and dissipation of fog-haze and smog when under cooling inside a deep coal mine were modelled using multiple Monte Carlo algorithm method validated by our experiment using a 1 m3 wooden chamber. Our numerical modelling was confirmed by our in-situ measurement results, indicating that (1) the bigger the condensation coefficient would lead to a faster formation of aerosol particles giving larger number and sizes of particles; (2) faster wind speed would reduce the number of aerosol particles and increase the geometric mean of the particle diameter. (3) When cooling in the tunnels, 2 m/s would be the lowest wind speed that could disperse the haze in the transport tunnels in the mine. The findings of our research should provide the theoretical basis for artificial cooling and controlling of the formation of haze in transport tunnels for mining.

Functional response of Fucus vesiculosus communities to tributyltin measured in an in situ continuous flow-through system

Hydrobiologia ◽  
1989 ◽  
Vol 188-189 (1) ◽  
pp. 277-283 ◽  
Author(s):  
C. Lindblad ◽  
U. Kautsky ◽  
C. André ◽  
N. Kautsky ◽  
M. Tedengren
Keyword(s):  
Functional Response ◽  
Continuous Flow ◽  
Fucus Vesiculosus ◽  
Flow Through

scholarly journals In situ monitoring of the influence of water on DNA radiation damage by near-ambient pressure X-ray photoelectron spectroscopy

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Marc Benjamin Hahn ◽  
Paul M. Dietrich ◽  
Jörg Radnik
Keyword(s):  
Dna Damage ◽  
Radiation Damage ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
In Situ Monitoring ◽  
Strong Increase ◽  
Oh Radicals ◽  
Strand Breaks ◽  
X Ray

AbstractIonizing radiation damage to DNA plays a fundamental role in cancer therapy. X-ray photoelectron-spectroscopy (XPS) allows simultaneous irradiation and damage monitoring. Although water radiolysis is essential for radiation damage, all previous XPS studies were performed in vacuum. Here we present near-ambient-pressure XPS experiments to directly measure DNA damage under water atmosphere. They permit in-situ monitoring of the effects of radicals on fully hydrated double-stranded DNA. The results allow us to distinguish direct damage, by photons and secondary low-energy electrons (LEE), from damage by hydroxyl radicals or hydration induced modifications of damage pathways. The exposure of dry DNA to x-rays leads to strand-breaks at the sugar-phosphate backbone, while deoxyribose and nucleobases are less affected. In contrast, a strong increase of DNA damage is observed in water, where OH-radicals are produced. In consequence, base damage and base release become predominant, even though the number of strand-breaks increases further.

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